Temporal Muscle Thickness Predicts Mortality and Disability in Older Adults Diagnosed with Mild Dementia.

Background: Sarcopenia contributes to increased hospitalizations, cognitive impairment, falls, and all-cause mortality. Current diagnostic methods, like body Magnetic Resonance Imaging and dual-energy X-ray absorptiometry, are costly and impractical. Notably, there is no standardized approach for assessing sarcopenia in dementia clinics. We studied the association of temporal muscle thickness (TMT) with key prognostic factors in people with Alzheimer's disease (AD) and Lewy body dementia (DLB).

Methods: We utilized data from the DemVest, a longitudinal cohort study, and included participants clinically diagnosed with mild AD or DLB. TMT was measured using baseline MRI scans. The main outcome measures were cognition, functional performance, malnutrition, and mortality. Various demographic and clinical factors were considered as potential confounders.

Results: The AD sample was mainly composed by females(76.9%), age 75.5(SD 6.95). The DLB sample was mostly composed by men(63.6%), age 75.8(SD 6.85). At baseline TMT showed significant association with cognitive performance in the DLB group (Est.=0.593, p-value=0.049). The longitudinal analysis revealed significant associations between TMT and functional decline in DLB (Est.=-0.123, p-value 0.007) and increased mortality in the whole sample(HR=0.815, p-value 0.002), the AD group (HR=0.834 p-value=0.031), and the DLB group (HR=0.767 p-value=0.019) respectively. These associations remained significant after adjusting for confounders.

Conclusions: The TMT measurement was associated with mortality in both dementia groups as well as with cognition and function in DLB. TMT emerges as a cost-efficient measure of muscle mass indicating clinical relevance and utility in healthcare settings. Implementing TMT assessment could improve patient care and aid in identifying individuals at risk of adverse outcomes in mild dementia.